Predominant Pollen and Spores

Alder season can start from the second week of March to the first week of April and end early to mid-June. The counts vary from low to high due to the number of species present and the effect of weather. The season with the highest counts can occur from late March to late April. The alder are considered important allergens.

Ash pollen season can last more than a month. The season can start early in warm years, like 2012, but generally the season startsthe first to third week of April and ends the mid to the end of May. The counts do get very high and can cause allergic reactions in sensitized individuals.

Beech season can vary a great deal from one year to the next. This is partly due to natural cycles and the effect of weather. The season can produce very few low counts to a season that can last well over a month and low to moderate counts are observed. The season can start late April to almost mid-May and end mid-May to early June. They may not cause reactions except in highly sensitized individuals.

The main birch season lasts more than a month and can start from late April to early May and end mid-May to early June with very high counts observed. They are important allergens, especially at these levels.

Cedars, junipers, and yews season can start from early to the third week of March. The season can end from the first to the third week of June. The counts can get very high. Most species in Canada do not cause allergic reactions.

Chestnut season varies from year to year in when the season happens and how much pollen is observed. This is partly due to natural cycles and the effect of weather. The season can start from early May to early June and end mid to late June. Mostly low with occasional moderate counts are observed. The amount of pollen observed varies according to the weather.

Elm season can start from the second week of March to early April and end late April to mid-May. The counts can get from the low to high range depending on the year and weather. At higher levels, this pollen can be allergenic.

Grass season is from late April to almost mid-October. Significant counts in the moderate and high ranges are observed from mid-May to late July.

Hemlock season can vary a great deal from year to year due to the effect of weather and cyclical patterns. The counts can range from low to moderate, depending on the year. The season can start from the second to third week of May and end late May to mid-June. Can cause allergic reactions in highly sensitized individuals.

Hickories have a season that can vary a great deal from year to year and can last from two to more than three weeks. The counts can be in the low to moderate range depending on the year. The season can start from early to late May and end the second to third week of June. The variation in season is partly due to the effect of weather. They can be considered important allergens.

The season for the linden and basswood season can vary from year to year and is also dependent on where the sampling location is situated. The season can start late June to almost mid-July and end mid to late July. Low and moderate counts are possible.

The season for the maple can start from the second week of March to early April and end mid to late May. The counts can reach high levels but the season varies from year to year, not only in when it occurs but also the pollen levels observed. Some of the species are considered allergenic.

Mulberries can have a very long season that can last over a month. The season can vary somewhat depending on where the sampling location is situated. The counts can get very high and can cause allergic reactions. The season can start from mid-April to early May and end late May to mid-June.

Nettles and parietaria pollen season can start mid-May to mid-June and end late September. The counts are in the low and moderate ranges. They are considered important allergens because of their small size.

Oak season can start from early to late April and end early to mid-June. The counts do get very high and some species are considered allergenic.

The season for the spruces, firs and pines varies from year to year due to the effect of weather. The season can last almost three months and can start mid-April to mid-May and end early to late July. Very high counts are observed and can be important in causing allergic reactions in individuals who are sensitized.

Plantains can play an important role in causing allergic reactions. The season can start from early to mid-June and end mid-September to early October. The counts do get in the moderate range.

Poplar, cottonwood, and aspen season can start early March in warm years like 2012. Generally the season starts from early to mid-April and ends early to late May. The counts can get in the very high range. They can cause allergic reactions at these levels.

Main ragweed season starts from the third week of July to early August with rare counts possible before these dates. The season ends with a heavy frost, which is well into October. Moderate and high counts are obtained from the second week of August to early October. They are considered important allergens.

The pollen season for the walnuts is highly affected by weather. The season can last well over a month and can start early to late May and end second to last week of June. Most years only low to moderate counts are observed but there are others where the counts are very high and the season lasts well over a month and a half.

Willows can start from the second to the third week of April and end mid to late May. Low, with the occasional moderate, counts are observed. May cause allergic reactions in individuals who are highly sensitized.

Some high counts of alternaria are observed and certain species are known to cause allergic reactions. The season with high counts is from April to mid-October.

Aspergillus spores are found throughout the whole counting season and are probably present in significant numbers beyond that. High counts are observed from late March to well into October.

Boletus counts do get high from June to early October and may be significant in causing allergic reactions.

Botrytis is considered an important allergen. Moderate counts are observed from May to late September.

Cladosporium is the most abundant spore found throughout the whole season. This spore exists all year round but very high counts are known to occur from March to late October.

Coprinus mushroom can produce some very high counts from May to mid-October. It is considered an important allergen. This fungus produces significantly higher counts at this site than at most other sampling locations.

Diatrypaceae counts are sporadic throughout the whole counting season. This fungus can produce very high counts from March to early October. They may not cause allergic reactions.

Some species of epicoccum are known to cause allergic reactions. The season is from April to late October with some high counts from July to mid-October.

Erysiphe, also know as powdery mildew, season is from mid-April to mid-October. Some high counts are observed. Allergenic properties are not well understood.

Fusarium counts are very sporadic from March to the end of September. The majority of the highest counts are observed from June to late September.

Ganoderma or bracket fungus can produce very high counts from June to late October. During the month of May, the counts are moderate to high. It is considered an important allergen.

Helicomyces season is from May to the end of September producing moderate and high counts. The season is very sporadic. Allergenic properties are not well understood.

Leptosphaeria season is April to mid-October with fluctuations in counts from day to day. This is probably due to the effect of weather. The highest counts are observed from June to the end of September. They can cause allergic reactions.

Moderate counts of myxomycetes are observed from March to mid-October.

Penicillium spores are found throughout the whole counting season and are probably present in significant numbers beyond that. High counts are observed from late March to well into October.

Moderate and high counts of pithomyces are observed from mid-June to late September.

Uredinales also know as rusts do not occur in really high numbers but not enough is known about their significance in causing allergic reactions at these levels. The season is from mid-May to mid-October.

Ustilaginales commonly referred to as smuts can reach high counts, but allergenicity is unknown. The season is May to late October.